The present invention is related to devices for charging objects during transport and, more specifically, to a device for placing a charge on an object and a method of retrofitting a conveyor for the device.
In many manufacturing, processing and packaging systems, it is desirable to place a charge on an object (often referred to as xe2x80x9cpinningxe2x80x9d an object) to aid in the proper stacking or alignment of various objects. For example, when stacking catalogs at the end of a conveyer, it is difficult to arrange for each of the catalogs to maintain its position so that the catalogs are positioned in a tight, vertically registered stack. The proper alignment of the catalogs is easier to maintain when a charge is placed on each of the catalogs. The tendency of charged catalogs to xe2x80x9cstickxe2x80x9d together facilitates transporting a stack of catalogs to another location for strapping and/or shrink-wrapping without catalogs slipping from the stack or becoming otherwise misaligned. Maintaining the catalogs in a properly aligned stack prevents damage to misaligned catalogs during the shrink-wrapping or strapping process.
Another situation in which it is useful to place a charge on objects is when card inserts are being dropped onto a card or sheet being transported along a conveyor. The use of static charge on either the card insert or the sheet aids in the proper positioning of the insert on the sheet. By placing a charge on the insert prior to dropping the insert onto the sheet, the insert is prevented from overshooting the desired placement location on the sheet and is less likely to be dislodged during further processing.
It can also be useful to place a charge on ribbons that are to be tacked together. When two ribbons are being processed so as to overlay each other, it is common for air to become trapped between the ribbons. By placing a static charge on the ribbons, air that is disposed between the ribbons can be displaced which helps prevent xe2x80x9cdog earsxe2x80x9d and creases in the tacked ribbons. In a similar fashion, placing a charge on a web can be used to firmly position the web on a roller and to reduce slippage between the web and the roller.
When trying to stack multiple sheets of paper prior to shrink wrapping, it is useful to place a static charge on the stack of sheets to bond the sheets of paper together and to keep them in a tight stack during the shrink wrapping process. Similarly, when interleaving a film between various layers of material, such as glass, paper or wood, it is useful to place a charge on the interleaved material to prevent slippage of various layers during the stacking process.
Static charges are also useful when manufacturing objects using in-mold decorating. Static charges can be used to pin a decorative decal tightly against the inner surface of a mold used in an injection molding process. This use of static charge greatly improves the finished product quality by preventing the decal from slipping or changing position in the mold.
While there are many processes that use static charge during the manufacturing packaging or processing of objects, conventional ionizing devices have many drawbacks. Referring to FIG. 1, a conventional ionizer 10xe2x80x2 is shown. Referring to FIG. 8, the ionizer 10xe2x80x2 has numerous pins 11 linearly aligned along an upper surface which project ions toward an object passing over the ionizer 10xe2x80x2. The ionizer 10xe2x80x2 is relatively tall as measured parallel to the pins 11 due to the orientation of resistors 13 in the device 10xe2x80x2. The relatively large height of the conventional ionizer 10xe2x80x2 increases the difficulty and expense of retrofitting a conveyor to include the ionizer 10xe2x80x2.
Another drawback of the conventional ionizer 10xe2x80x2 is that by using only a single row of pins 11, the dwell time of an object in the ionized area over the ionizer 10xe2x80x2 is short which prevents the placing of an adequate charge on objects having a UV coating, such as catalogs or the like. Dwell time is generally the amount of time each area of the object is exposed to ions emitted from the device 10xe2x80x2.
Another problem with the conventional ionizer 10xe2x80x2 is that the ion field created by the ionizer 10xe2x80x2 is not even. Each pin 11 emits ions in a generally conical fashion with the area closest to the center of the cone receiving a greater amount of ions. Thus, the resulting ion field from a conventional ionizer tends to have interspersed high and low ion concentrations as one moves along a direction parallel to the row of pins 11.
Referring to FIG. 8, the height of the conventional ionizer 10xe2x80x2 often makes it necessary to reroute the path of the conveyor belt 12 using additional rollers 70xe2x80x2 to accommodate the proper placement of the ionizer 10xe2x80x2. This increases the downtime of the conveyor during retrofitting and, correspondingly, increases the cost of installing the ionizer 10xe2x80x2.
What is needed, but so far not provided by the conventional art, is a device that is capable of placing a charge on an object passing by and proximate to the device, that provides an increased dwell time for objects passing by the device, that has a more evenly distributed ion field, that has a reduced height, and that is easier to retrofit into an existing conveyor. The present invention fulfills these needs.
Briefly stated, the present invention is directed to a device for placing a charge on an object passing by and proximate to the device in a first direction along a transport axis. The device includes a body having a surface. A first plurality of rows of ionizing pins is disposed in the body for emitting ions from locations proximate to the surface of the body. Each of the first plurality of rows of ionizing pins has a first row axis that is aligned generally parallel to the transport axis. The first plurality of rows of ionizing pins is positioned in a generally spaced apart side by side fashion. A second plurality of rows of ionizing pins is disposed in the body for emitting ions from locations proximate to the surface of the body. Each of the second plurality of rows of ionizing pins has a second row axis that is aligned generally parallel to the transport axis. The second plurality of rows of ionizing pins is positioned in a generally spaced apart side by side fashion. The first plurality of rows of ionizing pins and the second plurality of rows of ionizing pins are disposed so that at least a portion of the object moving in the first direction by and proximate to the surface of the body passes by and proximate to at least one of the plurality of rows of ionizing pins before passing by and proximate to at least one of the second plurality of rows of ionizing pins. The second plurality of rows of ionizing pins are laterally offset with respect to the first plurality of rows of ionizing pins so that the second plurality of rows of ionizing pins is generally aligned with positions between pairs of the first plurality of rows of ionizing pins. The object is charged by passing the object by and proximate to the surface of the body in the first direction to receive ions generated from both the first plurality of rows of ionizing pins and the second plurality of rows of ionizing pins.
The present invention is alternatively directed to a device for placing a charge on an object passing by and proximate to the device in a first direction along a transport axis. The device includes a body having a surface. A power input is disposed in the body. A plurality of resistors each has a longitudinal resistor axis and is capable of receiving power from the power input. Each of the plurality of resistors is disposed in the body with the longitudinal resistor axis being generally parallel to the surface. The plurality of ionizing pins is electrically connected to at least one of the plurality of resistors for receiving power to generate ions. The object is charged by passing the object by and proximate to the surface of the body in the first direction to receive ions generated by the plurality of ionizing pins.
The present invention is alternatively directed to a method of retrofitting a belt conveyor with a device to allow a charge to be placed on an object being transported in a first direction along a transport axis on the belt conveyor. The belt conveyor has a portion moving in the first direction for supporting and transporting the object. The device has a surface and is capable of emitting ions from locations proximate to the surface. The device includes a plurality of resistors each having a longitudinal resistor axis oriented generally parallel to the surface resulting in the device having reduced height as measured perpendicularly to the surface. The method includes positioning a device proximate to the belt conveyor, orienting the device so that the surface faces the portion of the belt conveyor moving in the first direction to allow the device to place the charge on the object being transported by the belt conveyor, and securing the device in position. The reduced height of the device simplifies the retrofitting of the belt conveyor to include the device.